Live clocks for Chicago and London, the exact difference as it stands today, a converter preset to this pair, and the full 24-hour comparison table — daylight saving handled on both sides.
Converting from Chicago time
The full day in Chicago on today, with the matching time in London:
| Chicago | London |
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Both clocks above are read live from the IANA time-zone database built into your browser — the same rule set your phone uses. “Difference today” is not a fixed fact about this pair of cities: it is computed from the two zones’ offsets right now, which is why it can legitimately read differently if you open this page in a different month.
London is 6 hours ahead of Chicago for most of the year. The US springs forward on the second Sunday of March while the UK waits until the last Sunday — for those weeks, and one week in the autumn, the gap is 5 hours instead.
The 24-hour table walks the whole of today in Chicago, hour by hour, and prints the matching moment in London — including the rows where London is still on yesterday, or already on tomorrow, which are marked +1 day or −1 day. Those edge rows are exactly the ones people get wrong doing the maths in their head.
Convert any moment between 44 world time zones, with offsets and DST handled.
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Free — try itLondon is 6 hours ahead of Chicago for most of the year. The US springs forward on the second Sunday of March while the UK waits until the last Sunday — for those weeks, and one week in the autumn, the gap is 5 hours instead.
3:00 PM — that is 9:00 AM in Chicago converted on a January day, when Chicago is on standard time (CST, UTC−6) and London is on GMT (UTC+0). Check it any time with the converter above: the answer is worked out from the two zones’ offsets on the date you pick, so it stays right when the clocks change.
Yes, on the clock-change dates. London is 6 hours ahead of Chicago for most of the year. The US springs forward on the second Sunday of March while the UK waits until the last Sunday — for those weeks, and one week in the autumn, the gap is 5 hours instead.
The overlap is Chicago’s morning against London’s afternoon: 8:00 AM–12:00 PM in Chicago is 2:00–6:00 PM in London. Chicago starts an hour later than New York against London, so the shared window is an hour shorter — book the joint calls before Chicago noon.
From timestamps and the IANA time-zone database inside your browser — the live rules for each zone, including daylight-saving start and end dates and southern-hemisphere seasons where relevant. Nothing is hard-coded: open this page on a clock-change day and the clocks, the difference and the 24-hour table all follow the new offsets automatically.
Two offsets and one subtraction — the same method the converter at the top of this page runs:
Take 9:00 AM in Chicago, on a January day, when Chicago is on standard time (CST, UTC−6) and London is on GMT (UTC+0). Adding the pair’s difference for that date gives 3:00 PM in London. The subtlety is that the difference itself is date-dependent for most pairs: repeat the same conversion in a month when one city has changed its clocks and the answer moves by an hour. That is why this page never prints a single fixed “the difference is X” without the word today next to it.
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